Ion Mobility Spectrometry (“IMS”) for the detection of chemical warfare agents (“CWAs”), toxic industrial chemicals (“TICs”), drugs, and explosives is primarily based on gas ionization by radioactive sources (e.g., 63Ni, 241Am, and 3H), since these sources meet requirements of a portable device for field use: small sized and lightweight, good mechanical stability, and do not require any additional power. Furthermore, they are very reliable while displaying a good sensitivity with regard to the detection of quite a large number of compounds of interest. However, for well-known reasons (e.g., radiation safety, regulation, record keeping, disposal problems) there is a growing interest in replacing radioactive sources by alternative gas ionization techniques.
One type of ionization source is a dielectric barrier discharge as ionizer, which has two metal electrodes separated by an insulator. However, in this configuration, one of the electrodes is exposed to the gas being ionized, which can lead to electrode erosion and gas contamination.